This invention relates to a crystalline package having a crystalline temperature resonator and a crystalline reference resonator housed within crystalline bodies that can withstand high pressures and temperatures such as found in deep oil or gas wells. The invention also includes a related method.
During drilling, completing and producing an oil or gas well, temperature and pressure measurements are typically taken from within the well to obtain information about the ability of the well to produce oil or gas. This can be done by lowering quartz crystal pressure and temperature transducers into the well and generating electrical signals in response to the frequencies at which the quartz crystal members oscillate in response to sensed pressure and temperature. Typically a quartz crystal reference member is also provided for compensating for changes in response dye to pressure or temperature. This reference member and the temperature sensing member can be housed together.
The previous combined temperature sensing resonator and reference resonator packaging being used in the oil and gas industry is an assembly of either (1) four Z-cut quartz plates or (2) three Z-cut quartz members with the center member having a central aperture. These are disposed to define a central cavity containing the reference and temperature resonators. See U.S. Pat. No. 4,802,370 to EerNisse et al. for example. The reference resonator in such embodiments typically includes an SC-cut quartz crystal which is essentially independent of pressure, and the temperature resonator typically includes a torsional mode quartz tuning fork. These types of packages are typically positioned adjacent quartz pressure crystals.
These previous types of packages are rated for use up to 16,000 pounds per square inch (psi) at 175 degrees centigrade (.degree. C.). At these maximums, package failures are encountered, usually resulting in separation or fracturing of the Z-cut quartz plates. Because pressures and temperatures exceeding these limits are encountered in oil and gas wells, there is the need for an improved temperature/reference package that is reliably functional above these prior limits.